Facing Thames Valley in Wanaka, an error-prone Otago was at one stage 13-0 behind in the first half before hooker Sekonaia Pole crossed near the 40-minute mark and first five Ben Miller nailed the conversion to make it 13-7 going into the sheds.
The hosts started to find their feet in the second half, and ran in several more tries to emerge 41-21 victors.
ORFU general manager Richard Kinley was among those watching on nervously, admitting he "didn't feel very settled" at the end of the first half.
He was pleased with the teams second half performance though, hoping it would be a catalyst for things to come ". . .they can only build from there".
James Lentjes, Miller, Aleki Morris, Dylan Nel and skipper Slade McDowall all crossed for Otago in the second half.
Winger Harry Lafituana scored two tries for the visitors - one in each half - who had first five Reece Boughton to thank for the rest of their points.
The match was played under overcast skies with the forecast heavy rain holding off until after the match had finished.
After their win, the Otago players were mobbed by children seeking autographs and just as many wanting to touch the old log o' wood.
- Additional reporting Kerrie Waterworth